What changed:
-------------

- Allow symlinks to be opened with O_PATH | O_NOFOLLOW.

- Allow the pathname argument to readlinkat(2) to be an empty string,
  provided the dirfd argument refers to a symlink opened with
  O_PATH | O_NOFOLLOW.  The readlinkat call then operates on that
  symlink.

- Support the Linux-specific AT_EMPTY_PATH flag for fchownat(2) and
  fstatat(2).

- Allow AF_LOCAL sockets to be opened with O_PATH.

- <signal.h>: New macro _NSIG replacing NSIG.  NSIG is now only
  visible to MISC builds, as on Linux.

- The new locale modifier @cjksingle allows enforcing of single-width
  character property for usually double-widthed characters.  This will
  be supported by upcoming mintty releases.  For the reasoning, see
  https://gitlab.freedesktop.org/terminal-wg/specifications/issues/9.


Bug Fixes:
----------

- Define CPU_SETSIZE, as on Linux.
  Addresses: https://cygwin.com/ml/cygwin/2019-12/msg00248.html

- Fix a regression that prevented the root of a drive from being the
  Cygwin installation root.
  Addresses: https://cygwin.com/ml/cygwin/2020-01/msg00111.html

- Many fixes in new pseudo console support.
  Addresses (among others):
	     https://cygwin.com/ml/cygwin/2019-12/msg00173.html
	     https://cygwin.com/ml/cygwin/2019-12/msg00292.html
	     https://cygwin.com/ml/cygwin/2019-12/msg00295.html
	     https://cygwin.com/ml/cygwin/2020-01/msg00093.html
	     https://cygwin.com/ml/cygwin/2020-01/msg00147.html
	     https://cygwin.com/ml/cygwin/2020-01/msg00161.html
